Sputtering target assembly and sputtering apparatus using...

Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering

Reexamination Certificate

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C204S298120, C204S298170, C349S187000

Reexamination Certificate

active

06824652

ABSTRACT:

This application claims the benefit of Korean Patent Application No. P2002-11193 filed on Mar. 02, 2002, which is hereby incorporated by reference for all purposes as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sputtering apparatus, and more particularly, to a sputtering target assembly and a sputtering apparatus using the same. The present invention is especially applicable in enhancing target utilization in a magnetron sputtering apparatus.
2. Description of the Related Art
Recently, image display units have changed from a cathode ray tube (CRT) display to a flat panel display such as liquid crystal display devices and plasma display panels. When compared to a cathode ray tube, a liquid crystal display device has lower power consumption, can be manufactured to be lighter and thinner, and does not radiate any harmful electromagnetic waves. Thus, the liquid crystal display device is well suited for the next-generation high-technology image display apparatus.
FIG. 1
is a schematic view showing a structure of a typical liquid crystal display device. Referring to
FIG. 1
, a typical liquid crystal display device includes a thin film transistor (hereinafter referred to as TFT) substrate, a color filter substrate, a liquid crystal layer, and a backlight unit. A TFT array is formed on the TFT substrate, and color filters are formed on the color filter substrate. The liquid crystal layer is formed between the TFT substrate and the color filter substrate. The backlight unit provides light to display an image.
Here, the TFT array formed on the TFT substrate transmits and controls an electrical signal, and the liquid crystal layer controls the degree or amount of transmittance according to an applied voltage. The light controlled through these procedures passes through the color filter substrate so that desired colors and images are displayed.
When a black matrix layer is formed on the color filter substrate or an electrode is formed on the TFT substrate, a metal such as chrome (Cr) is deposited using a sputtering apparatus. Here, in a thin film forming method using a sputtering process, a target formed of a desired thin film material is disposed within a vacuum chamber, and a substrate is disposed at a position corresponding to the target. Then, argon (Ar) ions are injected. Collision particles, such as argon (Ar) particles, ionized due to plasma formed within the vacuum chamber collide with a surface of a negatively charged target. Particles come off of the target or are sputtered due to the collision energy and are deposited on the substrate.
The thin film forming method using the sputtering process includes, for example, a diode sputtering method, a bias sputtering method, a high frequency sputtering method, a triode sputtering method and a magnetron sputtering method. In case of the widely used magnetron sputtering method, a magnet is mounted on the back surface of the target. Therefore, in the sputtering process, since a higher density of plasma is formed at a target region where the magnet exists than other regions, more target atoms are emitted, thereby enhancing the deposition rate of the thin film.
However, unlike these advantages, as the sputtering process is performed, a target erosion rate is high for a specific portion, which degrades the whole utilization of the target.
Presently, it is possible to implement various magnetron sputtering apparatuses.
FIG. 2
is a conceptional view showing an erosion state of the target according to the location of the magnet in a typical magnetron sputtering apparatus. As shown in
FIG. 2
, an erosion topology of the target
21
is different according to a location of the magnet
23
.
Referring to
FIG. 2
, when the sputtering process is performed using the magnet in the typical magnetron sputtering apparatus, a partial erosion of the target
21
occurs due to a uniform division of a magnetic field. Thus, the sputtering deposition is performed using only a portion of the target
21
, resulting in an ineffective utilization of the target.
To improve these disadvantages, a magnetron sputtering apparatus has been provided using a moving magnet, in which the fixed magnet
23
becomes a moving magnet. In such magnetron sputtering apparatus using a moving magnet, however, the target
21
still does not erode uniformly in all the regions. Moreover, the erosion occurs partially in a non-uniform manner.
Thus, to effectively use the target, the target is divided and is formed with different thicknesses according to the location of the target, taking into account the non-uniform erosion tendency of the target.
FIG. 3
is a schematic view showing a topology of a conventional sputtering target assembly employed in the typical magnetron sputtering apparatus. As shown in
FIG. 3
, targets
35
and
37
of a sputtering assembly
30
are divided with different thickness according to the location thereof. The targets
35
, which are formed to be relatively thick, are in regions where over-erosion occurs, and the target
37
, which is formed to be relatively thin, is in a region where less erosion occurs. Thus, a step topology is formed. By leveling the surfaces of the targets
35
and
37
and applying the step topology to an appropriate region of the backing plates
31
and
33
, a region of the backing plate
31
(in which only the back plate
31
is formed) corresponding to the over-erosion region
35
of the targets is protected and the utilization of the targets
35
and
37
can be enhanced and maximized.
Here, the erosion topology of the targets
35
and
37
is theoretically calculated for the magnetron sputtering apparatus and its operating condition. The degree of step of the backing plates
31
and
33
is determined according to the thickness of each location of the calculated targets
35
and
37
.
During the sputtering process in actual production using the magnetron sputtering apparatus employing the backing plates
31
and
33
(which are designed with the step thereon) an operating condition may be changed according to different production models. Such change in the operating condition also changes the theoretically calculated erosion topology of the targets. Here, a problem occurs in that the backing plates
31
and
33
should also be modified/redesigned so as to correspond to the newly changed operating condition.
Since the backing plates
31
and
33
are modified/redesigned according to the changed operating condition, the backing plates
31
and
33
tend to be articles of consumption in the production, which increases cost.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to sputtering target assembly and sputtering apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
Accordingly, an advantage of the present invention is to enhance the utilization of the sputtering targets.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a sputtering target assembly is provided including a backing plate having two evenly formed surfaces and a target having one portion evenly formed and on one surface of the backing plate and another portion having a different thickness from the one portion. The target can be made having a divided structure according to its thickness. Thus, different sections or portions of the target have different thicknesses. The target also has a region where there is a tendency for over-erosion, thus being formed relatively thicker.
According to another aspect of the present invent

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